There are many fastening assemblies in which parts are fastened together as an assembly by effecting a simple push-and-turn action of the parts relatively to one another.
An example is a standard bayonet connection.
Another example is given in our GB 2271216 where a connection, hereinafter described as being of the kind defined, includes a first part provided with a plurality of laterally extending projections which can be pushed into position between and then turned into engagement with respective slots formed in several other parts.
An object of the present invention is to improve security in the sense of improving resistance to accidental or unauthorised release.
According to one aspect of the present invention, a fastening assembly comprises a connection of the kind defined characterised in that at least one of the projections and/or at least one of the slots is adapted to give a wedging effect.
According to another aspect of the present invention, a fastening assembly comprises a connection of the kind defined characterised in that the slots are formed in protrusions located around an inner periphery of otherwise circular outline presented by a hollow member, and the projections are formed as arcuate sectors located around a plate-like member presenting an outer periphery of circular outline other than at recesses for receiving the respective protrusions.
It should be understood that references to slots incorporate references to grooves.
It should also be understood that a fastening assembly may incorporate both aspects of the present invention.
However, with particular regard to the aspect of the present invention involving the wedging effect, it is preferred that the wedging effect results from the slot/projection interengagement being non-planar rather than eccentric and, in particular, each of the projections may be formed as a ramp of increasing thickness with increasing turn into the slots.
One or more of the ramps may be of a ratchet-like construction, to further improve the resistance to release by co-operating with a locking rib presented by an associated one or more of the slots, and the ratchet-like construction may result from the formation of teeth. Alternatively, at least one of the slots may present a locking rib for sequential engagement with a series of locking ribs presented by at least one of the ramps, which may be an otherwise smoothly inclined ramp.
Preferably, each of the projections extends laterally outwardly and said other parts are formed integrally with one another.
Moreover, with particular regard to the aspect of the present invention involving the hollow member with inner protrusions and the plate-like member with outer recesses, it is preferred that at least one of the protrusions is hollow, opens to an outer periphery of the hollow member and extends axially of the hollow member.
The rest of the outer periphery of the hollow member between the protrusions may be threaded or ribbed as appropriate to permit engagement thereof by a standard nut or a nut-like member based on those disclosed in our WO 97/23934.
The plate-like member may also include, for example, a plurality of legs extending perpendicularly in a first direction to act as abutments. The legs may act as abutments for a component, such as a push button, carried by the plate-like member. Moreover, a pair of wings may extend perpendicularly in a second direction to assist manipulation when turning.
It should be appreciated that the plate-like member may be rotatably secured to another plate-like member which is not turned when the first-mentioned plate-like member is turned to engage the projections with the slots.
The interrupted circular outline for the outer periphery of the plate-like member is preferably only slightly smaller in diameter than the interrupted circular outline for the inner periphery of the hollow member to increase the overall strength and thus further improve the resistance to release particularly in applications where there is a risk of attack.